Conventionally, a seat belt system is mounted in a vehicle seat to protect an occupant in emergency situations such as a vehicle collision. The seat belt system includes a retractor attached to a vehicle rigid member to take up a seat belt.
This retractor is adapted to permit extraction of the seat belt when the seat belt is fastened around the occupant. The seat belt can also be extracted in a nonemergency situation so as not to restrain the occupant. In a vehicle collision or other emergency situations, the resultant impact or acceleration is sensed to cause a reel lock mechanism to lock a reel around which the seat belt is wound. Locking of the reel enables the seat belt to restrain the occupant or prevent sudden movement of the occupant to protect the occupant.
The reel lock mechanism is able to stop rotation of the reel per se. However, if the seat belt is loosely wound around the reel, then further extraction of the seat belt may occur, even if the reel is firmly locked. To prevent this, there has previously been proposed a seat belt retractor as shown in FIGS. 5 and 6. FIG. 6 is a sectional view taken on the line VI--VI in FIG. 5.
In FIG. 5, a seat belt retractor 201 comprises a frame 205 including a pair of side walls 202, 203 and a rear wall 204 extending between the side walls 202, 203, a pendulum 206 oscillatable when excessive impacts are applied, a ratchet 208 connected to a reel (not shown) around which a seat belt 207 is wound, a link 210 including a pawl 209 engageable with teeth of the ratchet 208 and moved up as the ratchet 208 is rotated, a first gripping member 211 mounted to the rear wall 204 of the frame 205, and a shaft 212 extending between the side walls 202, 203, and a second gripping member 214 including a support hole 213 (FIG. 6) at its one end to receive the shaft 212.
As the link 210 is moved up, the free end of the second gripping member 214 is moved toward the first gripping member 211. The seat belt 207 is then firmly sandwiched between the first gripping member 211 and the second gripping member 214 to prevent extraction of the seat belt 207 from the reel.
The shaft 212, the second griping member 214 and the frame 205 of the seat belt retractor 201 are all made of metal of high strength. When a vehicle is moved or vibrated, the shaft 212 is brought into metal-to-metal contact with the support hole 213 of the second gripping member 214 to cause undesirable sound. This sound makes a vehicle occupant not only feel uncomfortable, but also suspect that there may be some fault.
In the prior art, the second gripping member 214 may also be brought into metal-to-metal contact with the side walls 202, 203 of the frame 205 to cause similar undesirable sound.